Personal exposure sampling is the primary means to ensure that chemical and physical hazards in the workplace are maintained below occupational exposure limits. Typically few exposures are measured to represent a large working population because personal sampling is expensive and time consuming. Hence, most decisions regarding the extent to which workers are protected are based on extremely sparse data. Incorporation of distributed networks of inexpensive sensors has the potential to provide dramatic gains in the information content available for understanding the components of exposure variability, which are critical to evaluating and mitigating workplace risk. The laboratory and field work outlined in this application will develop and use a novel distributed monitoring network based on newly available, inexpensive aerosol sensors with worker tracking to estimate personal exposures. With successful completion of the proposed work, there will be many benefits, including information on operating and performance of inexpensive sensors and a network- deployable monitor (Aim 1), a method to optimize the number and placement of monitors within an occupational setting (Aim 2), and a method to integrate network and worker tracking data to estimate personal exposures (Aim 3). The new exposure assessment framework emerging from this development work will be applied in two year-long field studies at industrial workplaces to demonstrate its general utility and assess its reliability in diverse situations. Analyses of the dta from field studies is expected to demonstrate how the distributed monitoring network can be used to evaluate hazard risk at different time scales relevant to acute (e.g., 15-min) and chronic exposures (e.g., 8-hr, 40-hr, or longer; Aim 2). Further analyses conducted in Aim 3 are expected to show that network-derived personal exposures compare favorably to conventionally-measured personal exposures, approaching or meeting NIOSH criteria for method equivalence. Compared to conventional personal sampling, these new framework will enable an unprecedented increase in exposure measurements (1,000X to 10,000X). This dramatic increase in sample size, even if somewhat less accurate and precise than conventional sampling, will make comprehensive exposure assessment possible in routine industrial hygiene practice, medical surveillance, and epidemiological study. Moreover, the framework is sufficiently general to apply for any physical or chemical agent depending on sensor availability. Consequently, the results of this work will be directly applicable to many sectors of the National Occupational Research Agenda (NORA).